[1] > A [DFN@en[number value]] is a [[member]] of the [[type]] [CODE(JS)@en[[[Number]]]] and is a direct representation of a [[number]]. ;; [CITE[ECMAScript Language Specification (HTML version)]] ([TIME[2009-04-03 04:43:48 +09:00]] 版) [2] > The [[type]] [DFN[[CODE(JS)@en[[[Number]]]]]] is a [[set]] of [[values]] representing [[numbers]]. In [[ECMAScript]], the [[set]] of [[values]] represents the [[double-precision 64-bit format IEEE 754 values]] including the special “[[Not-a-Number]]” ([[NaN]]) [[values]], [[positive infinity]], and [[negative infinity]]. ;;[CITE[ECMAScript Language Specification (HTML version)]] ([TIME[2009-04-03 04:43:48 +09:00]] 版) [3] > A [DFN[[CODE(JS)@en[Number]] object]] is a [[member]] of the [[type]] [CODE(JS)@en[[[Object]]]] and is an [[instance]] of the [[built-in]] [CODE(JS)@en[[[Number]]]] [[object]]. That is, a [[[CODE(JS)@en[Number]] object]] is created by using the [CODE(JS)@en[[[Number]]]] [[constructor]] in a [CODE(JS)@en[[[new]]]] [[expression]], supplying a [[number]] as an [[argument]]. The resulting [[object]] has an implicit (unnamed) [[property]] that is the [[number]]. A [[[CODE(JS)@en[Number]] object]] can be coerced to a [[number]] [[value]] by calling the [CODE(JS)@en[[[Number]]]] [[constructor]] as a [[function]] (15.7.1). ;;[CITE[ECMAScript Language Specification (HTML version)]] ([TIME[2009-04-03 04:43:48 +09:00]] 版) [4] [CITE[Perlの数値処理 - Islands in the byte stream]] ([TIME[2011-09-29 11:25:55 +09:00]] 版)